<template>
  <div class="grid-view" ref="gridView">
    <slot></slot>
  </div>
</template>

<script>
export default {
  name: "GridView",
      props: {
		  cols: {
		    type: Number,
        default: 2
      },
      hMargin: {
		    type: Number,
        default: 8
      },
      vMargin: {
		    type: Number,
        default: 8
      },
      itemSpace: {
		    type: Number,
        default: 8
      },
      lineSpace: {
		    type: Number,
        default: 8
      }
    },
  mounted() {
    setTimeout(this._autoLayout, 20);
  },
  updated() {
    this._autoLayout();
  },
  methods: {
    _autoLayout() {
      //1.获取gridEl和children
      // 注: 这里为什么不用document.querySelector呢?
      // 答: 因为如果在项目中, 多处都用到了grid-view, 那么这里就不确定获取的是哪一个了.
    let gridEl=this.$refs.gridView; //获取div元素
    let children=gridEl.children;

    //2.设置gridEl的内边距
    gridEl.style.padding = `${this.vMargin}px ${this.hMargin}px`

    //3.计算item的宽度
    let itemWidth = (gridEl.clientWidth - 2 * this.hMargin - (this.cols - 1) * this.itemSpace) / this.cols;
     for (let i = 0; i < children.length; i++) {
          let item = children[i];
          item.style.width = itemWidth + 'px';
          if ((i+1) % this.cols !== 0) {
            item.style.marginRight = this.itemSpace + 'px'
          }
          if (i >= this.cols) {
            item.style.marginTop = this.lineSpace + 'px'
          }
        }
   },
  },
};
</script>

<style scoped>
.grid-view {
    display: flex;
    flex-wrap: wrap;
}
</style>